What's a simple, cheap treatment for my mononucleosis?

Rest. There is no good treatment for mono except time and rest.
Rest & good nutritio. There is no special meds for mono. The treatment is supportive & situational. Those who play contact sports or ride horses or bicycles should not do so if they have an enlarged spleen.(trauma can lead to rupture) appropriate rest and proper nutrition should allow the body to heal as fast as possible.In adults it can take weeks.